The precise nature of meat termed "ham" is controlled in a number of areas, often by statute, including the United States and European Union. In addition, numerous ham products have specific geographical naming protection, such as Prosciutto di Parma and Prosciutto Toscano PDO in Europe, and Smithfield ham in the US.

Definition

There are claims that the Chinese were the first people to mention the production of cured ham,[4] whilst Larousse Gastronomique claims an origin from Gaul,[5] but it was certainly well established by the Roman period, including an import trade from Gaul mentioned by Marcus Terentius Varro in his writings.[4]

The modern word "ham" is derived from the Old Englishham or hom meaning the hollow or bend of the knee, from a Germanic base where it meant "crooked". It began to refer to the cut of pork derived from the hind leg of a swine around the 15th century.[6] Preservation methods include curing, smoking, and salting.

Because of the preservation process, ham is a compound foodstuff or ingredient, being made up of the original meat, as well as the remnants of the preserving agent(s), such as salt, but it is still recognised as a food in its own right.[7]

Labeling

In many countries the term is now protected by statute, with a specific definition. For instance, in the United States, the Code of Federal Regulations (CFR) says that "the word 'ham', without any prefix indicating the species of animal from which derived, shall be used in labeling only in connection with the hind legs of swine".[8]

In addition to the main categories, some processing choices can affect legal labeling. For instance, in the United States, a "smoked" ham must have been smoked by hanging over burning wood chips in a smokehouse or an atomized spray of liquid smoke such that the product appearance is equivalent; a "hickory-smoked" ham must have been smoked using only hickory. However, injecting "smoke flavor" is not legal grounds for claiming the ham was "smoked"; these are labeled "smoke flavor added". Hams can only be labeled "honey-cured" if honey was at least 50% of the sweetener used, is at least 3% of the formula, and has a discernible effect on flavor. So-called "lean" and "extra lean" hams must adhere to maximum levels of fat and cholesterol per 100 grams of product.

Ham re-formed from smaller pieces into a larger block also has to be labeled in many jurisdictions.

Methods

Ham is produced by preserving and flavoring raw pork by salting, smoking, or wet curing. Besides salt, several ingredients may be used to obtain flavoring and preservation, from black pepper (e.g. Prosciutto Toscano PDO) to the precious saffron (e.g. the "Zafferano di San Gimignano PDO" in the esteemed Golden Ham).

Salting

Sea salt being added to raw pork leg as part of a dry cure process

Traditional dry cure hams may use only salt as the curative agent, such as with San Daniele or Parma hams, although this is comparatively rare.[9] This process involves cleaning the raw meat, covering it in salt (for about one month for Parma ham) while it is gradually pressed – draining all the blood. In Tuscan Ham (Prosciutto Toscano PDO) different spices and herbs (from garlic to black pepper, from juniper to laurel) are added to salt during this step. Specific ingredients may be used to enhance flavour and taste during this step, e.g. pure saffron in the Golden Ham from San Gimignano (Italy). The hams are then washed and hung in a dark, temperature-regulated place until dry. It is then hung to air for another period of time.

The duration of the curing process varies by the type of ham, with Serrano ham curing in 9–12 months, Parma hams taking more than 12 months, and Iberian ham taking up to 2 years to reach the desired flavour characteristics.[10] Some dry cured hams, such as the Jinhua ham, take approximately 8 to 10 months to complete.[11]

Most modern dry cure hams also use nitrites (either sodium or potassium), which are added along with the salt, although following a similar methodology. The nitrites deliver a distinctive pink or red tinge to the meat, as well as imparting flavour. The amount and mixture of salt and nitrites used has an effect on the shrinkage of the meat.[12]

Sodium nitrite is used because it prevents bacterial growth and, in a reaction with the meat's myoglobin, gives the product a desirable dark red color. Because of the toxicity of nitrite (the lethal dose of nitrite for humans is about 22 mg per kg body weight), some areas specify a maximum allowable content of nitrite in the final product. Under certain conditions, especially during cooking, nitrites in meat can react with degradation products of amino acids, forming nitrosamines, which are known carcinogens.[13]

Animal factors influencing enzymatic activity include age, weight, and breed.[16] During the process itself, conditions such as temperature, duration, water content, redox potential, and salt content all have an effect.[14]

The salt content in dry-cured ham varies throughout a piece of meat, with gradients determinable through sampling and testing or non-invasively through CT scanning.[17]

Smoking

Ham can also be preserved through the smoking method, in which the meat is placed in a smokehouse (or equivalent) to be cured by the action of smoke.

The main flavor compounds of smoked ham are guaiacol, and its 4-, 5-, and 6-methyl derivatives as well as 2,6-dimethylphenol. These compounds are produced by thermal breakdown (i.e., combustion) of lignin, a major constituent of wood used in the smokehouse.[18]

Wet curing

Wet curing (also known as brining) involves the immersion of the meat in a brine, sometimes with other ingredients such as sugar also added for flavour. Meat is submerged in the brine for around 3–14 days, during which time the meat needs to be kept submerged, and the brine mixture agitated periodically to prevent separation of the ingredients.[9]

Wet curing also has the effect of increasing volume and weight of the finished product, by about 4%.

The wet curing process can also be replicated by using mechanical pumping using needles and curing solution. This can be quicker, increase the weight of the finished product by more than immersion wet curing, and ensure a more even distribution of salt through the meat. This process is quicker than traditional wet cure, normally being completed between a few days and a few weeks.[19]

Protected designations

A number of hams worldwide have some level of protection of their unique characteristics, usually relating to their method of preservation and/or location of production or processing. Dependent on jurisdiction, rules may prevent any other product being sold with the particular appellation, such as through the European protected geographical indication.

Preserved ham can be cooked (although there is no requirement), and usually requires washing in water to remove salt. Whole fresh pork leg is also served cooked as gammon, known as ham in the United States.

Health effects

As a processed meat, there has been concern over the health effects of ham consumption.[26] A meta-analysis study has shown a statistically relevant correlation between processed meat consumption and the risk of pancreatic cancer, with an increase in consumption of 50 grams (1.8 oz) per day leading to a 19% increase in risk.[27]

A European cohort study also positively correlated processed meat consumption with higher all-cause mortality, with an estimation that 3.3% of the deaths amongst participants could have been prevented by consuming less than 20 grams (0.71 oz) of processed meat per day.[clarify][32]